1. Field of the Invention
This invention relates to a novel aqueously-swelling water stopper to be placed in a joint gap of structural members to fully fill up and close the joint gap for stopping water there. The invention also relates to a process of stopping water by using such water stopper.
More particularly, the invention relates to a water stopper having an outer resilient rubber layer made of aqueously-swelling water-stopping composition with a core having a high tensile strength, which rubber layer absorbs water and swells upon absorbing water to expand the volume thereof, and the invention also relates to a process of stopping water in architectural, civil engineering or other public structure (to be referred to as "building structure", hereinafter) by filling the aforementioned water stopper in a juncture gap or other gap of concrete or metallic structural member of the building structure, so that when water flows into the gap, the rubber layer swells to fully prevent water from seeping in or leaking out relative to the gap of the building structure.
2. Description of the Prior Art
In constructing various building structures, numerous water stoppers have been used, which are made of rubber, plastics, asphalt and the like. Such water stoppers of the prior art have shortcomings in that most of them have good adhesiveness but they are too soft and sometimes sticky, and that their properties vary with temperature variation, for instance, they become too hard in winter to be used in the field. Besides, after being used for a long period of time, the water stoppers of the prior art tends to reduce their resiliency or to become subject to creep phenomenon, so that the water stopper becomes less adaptable to fluctuation of structural gaps and fails to maintain full water stopping ability thereof.
It has been proposed recently to provide an aqueously-swelling water-stopping composition by adding aqueously-swelling organic substances to non-cross-linked rubber type water stoppers to improve the water-stopping ability thereof. The proposed water-stopping composition has difficulties in that, when the compounding ratio of the aqueously-swelling organic substance is low, sufficient water-stopping ability cannot be achieved, while if the compounding ratio thereof is too high, the dispersion of the aqueously-swelling organic substance in the rubber matrix becomes insufficient and the strength of the composition is considerably reduced. Besides, the aqueously-swelling organic substance is subject to hydrolysis, deterioration by oxidation, and decomposition, and its swelling ability tends to be weakened as the swelling and drying are repeated, and the residual low molecular weight components tend to cause poisonous effects.
Various new water stoppers are recently used at joints of concrete preformed members in the field of civil engineering constructions, such as junctions of box culvert segments and concrete flumes. Such new water stoppers are, for instance, those made of soft resilient asphalt, those having semi-hard plastics cores enclosed by soft adhesive mainly consisting of atactic polypropylene, those made of foam rubber or foamed plastics, of the foregoing water stoppers provided with adhesive layers disposed on all or a part of the outer surfaces thereof.
It is noted that joint portions of preformed concrete members are often made in socket-and-plug type or male-female type. Such joint portions sometimes cause water leakage, because of insufficient dimensional accuracy in spite of substantial overall uniformity of dimensions, improper field work at the construction site, or uneven sinking of the land.
The aforesaid water stoppers mainly consisting of resilient soft asphalt or atactic polypropylene have such a temperature sensitivity that, in winter they become too hard and their workability is reduced, while in summer they become too soft and sticky so that their workability is reduced in summer too. The foam structure and compressibility of the foam rubber or foamed plastics of the aforesaid water stoppers of the prior art are such that the water stoppers cannot fully absorb the dimensional inaccuracy and unevenness of the concrete surfaces. Such insufficient workabilities and properties of materials have been causes of water leakage in the prior art.